Faculty Publications
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Item Abstract Studies have been conducted on the effect of overstressing in rotary bending fatigue on the fatigue properties of an annealed and austempered ductile iron containing 1.5 Ni–0.3 Mo. For various R ratios S–N curves were determined and the fatigue limit estimated. It was found that the fatigue limit was a function of the level of overstressing and cycle ratio. In the case of austempered samples a beneficial effect of overstressing was observed at a certain level of overstressing. This was related to the work hardening behaviour of the austenite phase. In annealed samples, a reduction in the fatigue limit was observed at all levels of overstressing. Copyright © 1995, Wiley Blackwell. All rights reserved(EFFECT OF OVERSTRESSING ON FATIGUE BEHAVIOUR OF AUSTEMPERED DUCTILE IRON) Prasad Rao, P.; Padmaprabha1995Item Rotating bending fatigue tests were carried out on austempered ductile iron containing 1.5 wt% nickel and 0.3 wt% molybdenum. The ductile iron was austenitized at 900 or 1050 °C and then austempered at 280 or 400 °C for different lengths of time to obtain different microstructures. The fatigue strength was correlated with the amount of retained austenite and its carbon content, which were both determined by X-ray diffraction technique. While the tensile strength decreased with increasing retained austenite content, the fatigue strength was found to increase. Carbide precipitation was found to be detrimental to fatigue strength. Lower austenitizing temperature resulted in better fatigue strength. © 1994 Chapman & Hall.(Kluwer Academic Publishers, Effect of microstructure on the fatigue strength of an austempered ductile iron) Shanmugam, P.; Prasad Rao, P.; Rajendra Udupa, K.; Venkataraman, N.1994Item Flexural fatigue analysis of steel fibre reinforced concrete(2012) Girish, M.G.; Chandrashekar, A.; Ravi Shankar, A.U.This paper presents the experimental investigation carried on Steel Fiber Reinforced Concrete (SFRC) subjected to repeated loading. The SFRC beam specimen of size 500mm × 100mm × 100mm containing mixed steel fibers of size 50mm × 2mm × 0.6mm and 0.5mm?× 30mm in different proportions were tested under two point flexural fatigue load at a frequency of 2Hz at various stress levels. The readings obtained from the flexural fatigue test were used to plot S-N diagram and also to perform statistical analysis using two parameter Weibull distributions. © 2012 CAFET-INNOVA TECHNICAL SOCIETY.Item Fatigue and Engineering Properties of Chemically Stabilized Soil for Pavements(Springer, 2013) Lekha, B.M.; Ravi Shankar, A.U.; Goutham, G.Soil stabilization is a technique to improve the weak soils and making them to meet certain requirements of the specific engineering projects. The type of soils available in Dakshina Kannada region of Karnataka State is laterite and Lithomarge clay. Its Plasticity Index is very high due to the presence of high percentage of silt and clay content. In the present investigation, an attempt is made to study the behaviour of laterite with and without adding chemicals. A chemical named Zycosoil, when added to water and mixed with soil alters its engineering properties that depend upon the type of the soil and dosage of chemical. These chemicals are liquid additives, which act on the soil to reduce the voids between soil particles and minimize adsorbed water in the soil for maximum compaction. In the present study, the effectiveness of Zycosoil in stabilizing the laterite soils of South Canara district is investigated through laboratory experiments. Various geotechnical properties are studied and correlations between different geotechnical properties and improvement in the soil properties with different percentages of chemical additions are derived. The important properties such as index properties, compaction characteristics, unconfined compressive strength parameters, California bearing ratio values and fatigue behaviour were studied. The results obtained indicate that there is an improvement in almost all properties with the addition of Zycosoil. © 2012 Indian Geotechnical Society.Item Influence of equal channel angular pressing and laser shock peening on fatigue behaviour of AM80 alloy(Elsevier B.V., 2019) Praveen, T.R.; Shivananda Nayaka, H.S.; Swaroop, S.AM80 magnesium alloy was processed with Equal Channel Angular Press (ECAP)for grain refinement. Laser shock peening without coating (LSPwC)were executed on ECAP processed sample at 8 GW cm?2 and further grain refinement were observed at surface. SEM image expose the grain refinement at different stage of processing, and fine grains of sub-micron size were observed at surface level after ECAP + LSPwC. Residual stress were measured using X-ray diffraction, sin2(?)method and compressive residual stress was found after ECAP. LSPwC intensify the compressive residual stress at surface. Increases in magnitude of residual stresses were noticed with 200 and 300% of LSPwC. Increase in surface roughness were noticed from 0.6 to 6.8 ?m by increasing the percentage of LSPwC coverage. Fatigue tests were acknowledged the effect of ECAP and ECAP + LSPwC on reliability of grain refinement technique. ECAP sample showed fatigue life of 7539 cycles against as received. Highest fatigue life of 85,268 life cycles was observed with ECAP + LSPwC by 100% of coverage. Further process of LSPwC for 200 and 300%, fatigue life was significantly decreases to 22,987 and 384 cycles respectively. SEM images of fractured surface exhibits effect of ECAP and LSPwC on crack initiation and propagation for failure. © 2019 Elsevier B.V.Item Effect of cryogenic grinding on fatigue life of additively manufactured maraging steel(MDPI AG, 2021) Balan, A.S.S.; Kannan, C.; Kumar, A.V.; Hariharan, H.; Pimenov, D.Y.; Giasin, K.; Nadolny, K.Additive manufacturing (AM) is replacing conventional manufacturing techniques due to its ability to manufacture complex structures with near?net shape and reduced material wastage. However, the poor surface integrity of the AM parts deteriorates the service life of the components. The AM parts should be subjected to post?processing treatment for improving surface integrity and fatigue life. In this research, maraging steel is printed using direct metal laser sintering (DMLS) process and the influence of grinding on the fatigue life of this additively manufactured material was investigated. For this purpose, the grinding experiments were performed under two different grinding environments such as dry and cryogenic conditions using a cubic boron nitride (CBN) grinding wheel. The results revealed that surface roughness could be reduced by about 87% under cryogenic condition over dry grinding. The fatigue tests carried out on the additive manufactured materials exposed a substantial increase of about 170% in their fatigue life when subjected to cryogenic grinding. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Item Mechanical properties of MWCNTs and graphene nanoparticles modified glass fibre-reinforced polymer nanocomposite(Springer, 2021) Seshaiah, S.; Reddy, K.V.K.; Sahu, R.K.; Katiyar, J.K.In the present study, the multi-walled carbon nanotubes (MWCNTs) and graphene nanoparticles were used as a reinforcement to fabricate glass fibre polymer composite at different orientations (unidirectional glass fibres 0° and 90°; woven glass fibres 0°/90° and 45°/45°). The composites were developed using hand lay-up-assisted vacuum bagging method at 1 torr pressure. The concentrations of nanoparticles (~diameter 5–20 nm) were varied in the range of 0.1–0.3 wt% in the matrix. The mechanical properties like impact strength, tensile strength and fatigue strength were carried out on Izod and Charpy machine, universal testing machine and computer-controlled machine under sinusoidal wave, respectively. It is observed that the glass fibre/epoxy composite blended with MWCNTs/graphene by 0.2 wt% has shown higher fatigue life by 56%, higher tensile strength by 36% and higher capability of energy absorption by 927.7% in notched type and lower capability of energy absorption by 155.43% in un-notched type, as compared to pure composite. The increment in properties is due to the better bonding between fillers and matrix. However, the increase of MWCNTs and graphene nanoparticles by wt% in composite laminates have shown lower fatigue strength because of the agglomeration of MWCNTs particles in matrix that caused the propagation of fatigue cracks under cyclic loading. Further, the damage behaviour of composite materials was analysed using scanning electron microscopy. It is found that a different damage behaviour in each composite is observed which is attributed to the matrix cracking, fibre rupture, fibre pullout, fibre split and fibre de-bonding. © 2021, Indian Academy of Sciences.Item An experimental evaluation of the microstructure, mechanical and functional fatigue properties of the boron-doped Cu-Al-Be SMA wires(Elsevier Ltd, 2021) Singh, R.K.; Biswas, P.; Murigendrappa, S.M.; Kattimani, S.An experimental evaluation of the microstructure, mechanical and functional fatigue properties of the Cu-11.70Al-0.45Be doped with Bx (x = 0.05, 0.10, 0.12, and 0.14 wt%) SMA wires has been carried out. The experiments were performed to investigate microstructure, phase/precipitates, and transformation temperatures for both as-cast and wire samples. Furthermore, tensile properties, shape recovery ratio, and functional fatigue evaluation have also been carried out for the wire samples. The investigation shows that the addition of the minor amount of boron and secondary processes involved during the specimen preparation induced excellent grain refinement. The addition of boron decreased transformation temperatures; however, there was not a considerable change observed due to the secondary process. It was observed that tensile properties increases with the boron addition, and complete shape recovery was observed for all the selected alloys. Finally, functional fatigue tests were conducted under constant stress condition and observed that the number of cycles until the failure has increased and more distance recovery was achieved with an increase in boron doping. © 2021Item Influence of NMAS and groove depths on the static and fatigue shear performance of aggregate interlocking in PQC mixes(Taylor and Francis Ltd., 2022) Bellary, A.; Suresha, S.N.In the present study, a new test methodology is proposed to characterise the shear transfer ability of aggregate interlocking in pavement quality concrete (PQC) cylindrical specimens by conducting the direct shear test in the laboratory. The influence of the nominal maximum aggregate size (NMAS) and groove depth (GD) on shear strength (τ), joint shear stiffness (K) and fracture energy mode–II (G IIF) of aggregate interlocking in pavement quality concrete (PQC) are studied under static loading. A relationship between G IIF and K is determined. Also, shear fatigue test is conducted at higher stress levels to evaluate the effect of NMAS and GD on the performance of aggregate interlocking in PQC specimens at the grooved cross-section. From the Anderson–Darling statistic test, it is found that obtained fatigue results follow three-parameter Weibull distribution. The shape parameter (β) of the distribution is between one and two, which indicates that failure is due to wearing action. It is concluded that the proposed method in this research can be effectively used to evaluate τ, K and G IIF of aggregate interlocking in PQC specimens. Also, the use of larger NMAS in the PQC mix significantly improves the performance of aggregate interlocking under shear fatigue loading. © 2021 Informa UK Limited, trading as Taylor & Francis Group.Item Comparison of the Experimental and Modelling Results of Mechanical Characteristics of LM6 and LM9 Alloy for Tractor Application(Springer, 2023) Shetteppanavar, C.C.; Shinde, R.B.; Hanumanthappa, H.; Mohanraj, G.T.; Shanmugam, B.K.S.; Srivatsav, S.K.Y.; Kavitha Kumar, A.R.B.K.In India, the development of composite and alloys material has provided the required characteristics material. In this study, an attempt has been made to compare the performance of LM6 and LM9 alloy for an automobile application. These alloys are studied based on the tensile strength and fatigue test required for the pullet used in tractor application. The tensile test results showed that the LM9 alloy specimen has higher strength than the LM6 alloy specimen. Furthermore, results showed that the fatigue strength of the LM9 alloy specimen was found to be higher than the LM6 alloy specimen. Further, the tensile and fatigue materials behaviour of LM6 and LM9 specimens were compared through ANSYS modelling. From the experimental and modelling results, it was clear that the modelling results are in close agreement with the tensile and fatigue experimental results. The mechanical characteristics such as tensile and fatigue strength of the LM9 specimen were found to be much better than the LM6 specimen. The microstructural analysis also showed higher silicon particles providing higher strength for LM9 specimens than LM6 specimens. The pulley material made out of LM9 alloy will avoid the shear failure occurrence of the pulley. © 2022, The Institution of Engineers (India).